Manual sanding machine tool

ABSTRACT

A manual grinding tool, in particular an oscillating sander ( 10 ), with a housing ( 12 ) and an abrasive sheet carrier ( 14 ), against the working surface ( 15 ) of which an installable abrasive sheet ( 16; 150 ) rests, whereby said abrasive sheet is installed using clamping means ( 20, 23; 360, 500 ) which clamp opposite abrasive sheet ends ( 17, 19; 155 ) to the abrasive sheet carrier ( 14 ), is made easier to operate and handle because it is lighterweight and more effective by the fact that the clamping means ( 20, 23; 350, 500 ), together with an abrasive sheet end ( 17; 155 ) clamped thereto, are capable of being moved away from the diametrically opposed abrasive sheet end ( 19; 155 ) which is also clamped thereto, so that said abrasive sheet is locked under tensile stress, whereby the clamping means are composed of resilient material.

BACKGROUND INFORMATION

The present invention concerns a manual grinding tool according to thegeneral class of claim 1.

An orbital sander with a sanding plate on which abrasive sheets areinstalled is made known in GB patent publication 23 22 582; the abrasivesheets are capable of resting with their back against the underside ofthe sanding plate and are clampable in place on their top side. Theunderside of the abrasive sheets, where sanding means are provided,faces downward/outwardly and, when the abrasive sheet carrier is mountedon a workpiece, it is usable for sanding.

The operator must use both hands to clamp the abrasive sheets in place,and the hand power tool should be placed on a solid surface. Using onehand, one end of the abrasive sheet is inserted into a slit between anopened clamping jaw and the top side of the abrasive sheet carrier, andthe clamping jaw is held open in the release position until the end ofthe abrasive sheet is inserted so that it closes via spring force whenthe clamping jaw is released. This is the clamped position in which theabrasive sheet end is fixed. The abrasive sheet is automaticallytightened to a certain extent in that the rotatably mounted clamping jawtries to roll away from the abrasive sheet end, thereby carrying italong, due to an inclined-plane contact surface on the top side of theabrasive sheet carrier.

The same procedure is used with the other abrasive sheet end as is usedwith the first abrasive sheet end, whereby the clamping force andtightening force of the clamping means are limited.

The same disadvantages also apply for the abrasive sheet clamping systemaccording to U.S. Pat. No. 3,540,161.

ADVANTAGES OF THE INVENTION

The manual grinding tool according to the present invention having thecharacterizing features of claim 1 has the advantage of particularlyconvenient, rapid clamping—combined with the abrasive sheet beingstretched tight—using only one hand, with simplified manufacture of theclamping means at lower cost and significant weight reduction. Thisresults in increased abrasive performance and greater overall efficiencyof the manual grinding tool.

Due to the fact that the first abrasive sheet end is capable of beinginserted using just one hand into a self-opening slit and isautomatically clampable there, and, subsequently, the second abrasivesheet end is insertable—also using just one hand—into the clampingdevice and is then capable of being stretched tight, to the tearinglimit, the abrasive sheet is capable of being fixed quickly and safelyagainst misuse between the two clamping points and the working surfaceof the abrasive sheet carrier in such a manner that it is stretchedtightly and, during sanding, a relative motion between the abrasivesheet carrier and the abrasive sheet is largely prevented.

Due to the fact that the slit which clamps the first abrasive sheet endis opened using a single, central, easily located operating button torelease the abrasive sheet, the operating comfort of the manual grindingtool is particularly high.

Due to the fact that one of the clamping means is configured as tongs,between the clamping jaws of which an abrasive sheet end is clampable,and due to the fact that the tongs—together with the clamped abrasivesheet end—are movable around a swivel axis and are lockable in an endposition, secure clamping followed by stretching-tight of the abrasivesheet is attainable in a convenient and reliable manner using simplemeans.

The tongs have the advantage that abrasive sheets of any thickness areclampable with maximum clamping force, because a long closing pathenables all dimensional differences to be compensated for in a sensitivemanner, whereby the clamping force attained is stronger than has beenpreviously achieved. In addition, abrasive sheets having differentlengths—within limits—can be installed on the hand power tool, because along overhang can easily form between the open active clampingjaw—configured in the shape of a half ring or bracket—and the passiveclamping jaw, and it can be comfortably accommodated there.

Due to the fact that the passive clamping jaw is configured ascorrugated spring sheet which is capable of being deformed around abending region in the manner of a hinge, the one end of which is clampedto the housing in the manner of a transverse beam, and the free end ofwhich has a friction lining, in particular rubber, the desired flatspring characteristic (a small force/travel ratio) with extremely shortinstallation length of the passive clamping jaw is attainable in aspace-saving fashion.

Due to the fact that the passive clamping jaw—as viewed from the freeend, from right to left—first extends upwardly as a sine wave followedby a semi-sine wave having a smaller amplitude, the corrugated springsheet is reliably clampable with the desired spring force.

Due to the fact that the active clamping jaw is part of a two-armedclamping lever, one of which said clamping levers serves as a handlewhich is detachably lockable in the clamped position in an over-latchingmanner, and due to the fact that the tongs, to this end, are pivotablearound the swivel axis between two end positions that define the clampedand released positions, it is particularly easy to install an abrasivesheet.

Due to the fact that the clamping lever can be pivoted into its holdingposition in an over-latching manner via an over-latching hook bentinwardly toward the housing in the manner of a barb, the tongs arelockable in a particularly comfortable and operationally-reliable mannerby pressing the clamping lever perpendicularly and/or they are capableof being released in a failsafe manner by pressing them toward thehousing in a self-locating manner.

Due to the fact that, with the tongs in the clamped position, the activeclamping jaw rests against the passive clamping jaw with a minimumclamping force achievable with spring means, the clamping force at theabrasive sheet end to be clamped is capable of being determined byselecting the appropriate elastic means.

Due to the fact that the active clamping jaw is bent in the manner of ahalf ring and grips around the passive clamping jaw in such a mannerthat it rests against the outside of the passive clamping jaw to clampthe abrasive sheet and carries it along when pivoted into the clampedposition, a user-friendly clamping-tightening mechanism with reducedrisk of injury when replacing the abrasive sheet and/or working with themanual grinding tool is created, because protruding edges on the manualgrinding tool are prevented. A defined spring load-deflection curve ofthe active clamping jaw is achieved via its bracket or arch-shapedconfiguration having a certain wire diameter, so that a maximum clampingforce between the clamping jaws is established in the clamped position.

Due to the fact that the passive clamping jaw has a full-lengthlongitudinal notch to accept the active clamping jaw, the grip betweenthe passive clamping jaw and sandpaper end is improved and the clampingforce is strengthened further.

Due to the fact that, in addition to the tongs for the one abrasivesheet end, clamping means for the other abrasive sheet end are provided,which said clamping means act in a manner such that they allow theabrasive sheet to enter in a preferred direction, but release in thereverse direction with special actuation, it is possible to clamp theabrasive sheet quickly using just one hand.

In this case, one-hand operation means that, in fact, only one hand needbe active to insert and fix the abrasive sheet. The other hand can beused alone to fix the hand power tool, e.g., to press it against a base.

Due to the fact that the clamping jaws are composed of elastic,rubber-like material, the clamping servo effect becomes stronger as theclamping of the abrasive sheet increases. This servo effect is alsostrengthened by the fact that the outer contour of the clamping jaw isbent progressively with a small variation in pitch.

Due to the fact that the clamping jaws are composed of sheet metaland/or wire and are provided with a rubber coating, they areeasy-to-manufacture, lightweight and functionally reliable.

Due to the fact that the clamping jaw and/or the active clamping jaw areinsertable in a groove in the housing and are secured against coming outby means of a screw which extends partially over the groove, a highdegree of functional safety of the tongs is achieved with little effortwhen the sandpaper is clamped.

Due to the fact that the clamping jaw is positioned horizontally and theinsertion slit must be opened wide—whereby it can even lie below theplane of the sanding plate—the abrasive sheet need not be angled upwardor bent to be inserted into the slit; instead, it can be inserted in aself-locating, extremely convenient—“blindly”, even—very casual manner,and then stretched tight.

Due to the fact that the clamping lever is approximately 60 mm long andthe 2 active jaw has a lever length of approximately 20 mm, aconvenient, secure clamping of the abrasive sheet is possible.

DRAWING

Exemplary embodiments of the invention are described in greater detailin the subsequent description with reference to an associated drawing.

FIG. 1 shows a side view of the manual grinding tool according to theinvention with clamping device,

FIG. 2 is a top view at an angle from above of the abrasive sheetcarrier of a further embodiment of the manual grinding tool withclamping device,

FIG. 3 is the underside view according to FIG. 2,

FIG. 4 is a further exemplary embodiment of the manual grinding toolaccording to the invention,

FIG. 5 is a spacial representation of the active clamping jaw made ofwire, shown alone,

FIG. 6 is an active clamping jaw end, shown alone,

FIG. 7 is an exemplary embodiment of the active clamping jaw end,

FIG. 8 is another exemplary embodiment of the active clamping jaw end,

FIG. 9 is an exemplary embodiment of a passive clamping jaw made ofwire,

FIG. 10 is a further exemplary embodiment of a clamping jaw made ofspring wire and spring sheet, and

FIG. 11 is the exemplary embodiment according to FIG. 11 with openedclamping jaw.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a manual grinding tool 10 (orbital sander) with a housing12 that has a handle on the outside and an electric motor on the inside(not shown). An abrasive sheet carrier 14 is located at the bottom ofhousing 12, which said abrasive sheet carrier, driven by a motor, iscapable of being set into oscillating motion relative to housing 12 and,as a result, can remove material from a work piece (not shown) viasanding with an abrasive sheet 16 secured tightly below on its workingsurface 15. The grinding dust that is created is capable of being blownout and/or suctioned up from the front side 121 toward the rear side 122of manual grinding tool 10 via suction connecting piece 120. Abrasivesheet 16 rests with its back side against the underside of abrasivesheet carrier 14.

A clamping means designed as a two-armed clamping lever 20 with a swivelaxis 24 is positioned in the front on the top side 13 of abrasive sheetcarrier 14. Above swivel axis 24, clamping lever 20 is a swing arm and,below said swivel axis, it is a clamping jaw 22. It rests with its outercontour 27 bent in the shape of a saber against locking face 23 of topside 13 of abrasive sheet carrier 14. Swivel axis 24 of clamping lever20 is located on a bracket 28 on the top side of abrasive sheet carrier14.

A tension spring 26 bears between the top side of swing arm 21 and anabutment (not shown) in housing 12, which said tension spring can alsobe configured as a leg spring; it tries to pivot clamping lever 20 inthe clockwise direction, whereby it presses clamping jaw 22 againstlocking face 23 and thereby clamps abrasive sheet end 19 in place.

In the upper region, swing arm 21 has a single, projecting knee servingas push button 211. By means of this, swing arm 21 is capable of beingmoved downward using a finger, whereby tension spring 26 is loaded.Clamping jaw 22 then lifts away from locking face 23, and the gapbetween outer contour 27 and locking face 23 opens so wide that abrasivesheet end 19 is released and can be removed.

The distance between swivel axis 24 of clamping lever 20 and lockingface 23 is smaller than the distance between swivel axis 24 and theradially outermost point of outer contour 27, so that, in the positionwith spring preload via spring 26, clamping jaw 22 bears against lockingface 23 on the top side 13 of abrasive sheet carrier 14. As a result,the clamping force on abrasive sheet 16 increases in proportion to theforces that try to release abrasive sheet 16 against the direction ofinsertion.

Tension spring 26 is preloaded to such a low extent that, when outercontour 27 of clamping jaw 22 is tapped even slightly, abrasive sheet 16displaces said clamping jaw from the outside against the direction oftension, creates the gap by itself which is needed for insertion, and iseasily inserted and pushed back with one hand.

Clamping jaw 22 is composed at least partially of elastic, rubber-likematerial with a high coefficient of friction that limits relative motionbetween abrasive sheet 16 and clamping jaw 22.

As viewed on the right, a clamping-tightening device configured as tongs34 is located on the rear side 122 of abrasive sheet carrier 14. It iscomposed of a clamping lever 35 with curved active clamping jaw 36 and ahandle 39 that is a two-armed lever which is pivotable around a swivelaxis 40. Active clamping jaw 36 is composed of elastic material, e.g.,spring steel. Also capable of being pivoted around swivel axis 40 is aclamping lever 37 that forms passive clamping jaw 38 and bears againstthe inner contour of active clamping jaw 36 when abrasive sheet 16 istightened. The other abrasive sheet end 17, which is diametricallyopposed to abrasive sheet end 19, is inserted and retained betweenpassive clamping jaw 38 and active clamping jaw 36.

When tongs 34 with retained sandpaper end 17 are pivoted around swivelaxis 40 in the counterclockwise direction, its distance from the othersandpaper end 19 increases. As a result, abrasive sheet 16 is tightenedand pulled taut against the underside of abrasive sheet carrier 14. Thetightening of abrasive sheet 16 is apparent in rear lower edge 118 ofcushion that is pressed round in shape.

When tongs 34 are in the clamped position, clamping lever 35 assumes anend position in which handle 39 is snapped into locking groove 49 in therear and/or lateral latching hook. By pressing latching hook 48 backwardwith the thumb and/or by pivoting handle 39 out of locking groove 49against spring 50, clamping lever 35 is released; it can pivot back intoits open position with spring preload via spring 42. Following saidclamping lever, passive clamping jaw 38—acted upon by a furthercompression spring 44—moves into its own end position. Clamping lever35, under spring preload, continues to pivot past this point until itscontact surface 51 bears against the top side 47 of passive clamping jaw38. In this stop position, tongs 34 are wide open, and the distancebetween active clamping jaw 36 and passive clamping jaw 38 is so greatthat sandpaper end 17—indicated with the dashed line—can be insertedinto tongs 34 quasi blindly.

Compression spring 44, which applies preload to passive clamping jaws38, determines and/or limits the clamping force between active clampingjaw 36 and passive clamping jaw 38.

If clamping lever 35 is released from its clamped position by releasinglatching hook 48 and is pivoted around axis 40 in the clockwisedirection to replace the abrasive sheet, the distance between theclamping points of sandpaper ends 17, 19 becomes shorter once more,thereby releasing tension from abrasive sheet 16, allowing it to beeasily removed.

FIG. 2 shows a spacial depiction of a further exemplary embodiment ofabrasive sheet carrier 114 and manual grinding tool 10 according to FIG.1 as a top view diagonally from the front. A clamping lever 200 islocated on front side 121, as viewed on the right, which said clampinglever essentially corresponds to that in FIG. 1, although it has aseparate actuating button 2110 that is supported in an abutment 600 in amanner that allows it to pivot around an axis of rotation 610 and bearselastically against the housing (not shown) via a compression spring(not shown).

When button 2110 is actuated in the direction of arrow 333, the part ofbutton 2110 located above axis 610 moves toward the housing. The partlocated below axis 610 pivots outwardly, whereby it bears against thetop part of clamping lever 200. When button 2110 is actuated, saidclamping lever is pivoted outwardly in the clockwise direction, so thatclamping jaw 220 lifts away from locking surface 230 and an abrasivesheet end clamped therebetween can be removed, because clamping force isno longer applied.

To enhance understanding of FIG. 2, reference is made to the parts inFIG. 1 having the same function and configuration. The first numeral inthe reference numbers in FIG. 1 is duplicated and placed in front of thereference numbers of the equally-acting parts in FIG. 2 to distinguishthem from yet match them to the reference numbers in FIG. 1.

As viewed on the left, abrasive sheet carrier 114 has tongs 334 on itsrear side 122, which said tongs essentially correspond to the tongs 34explained in reference to FIG. 1, but the details of which have adifferent configuration. A clamping lever 335 for pivoting tongs 334 islocated on only one side of abrasive sheet carrier 114, and it issupported on this side at a stop 445 in a springy, latching manner.

Tongs 334 are shown in the clamped state, in which their clamping pontand/or an abrasive sheet end (not shown) has been pivoted to thegreatest possible distance away from clamping lever 200 on thediametrically opposed side of abrasive sheet carrier 114.

FIG. 3 shows the details of abrasive sheet carrier 114 according to FIG.2 at an angle from the rear underside, whereby the configuration ofactive clamping jaw 336 in interaction with passive clamping jaw 338 isclearly shown. In the clamped position shown, they bear against eachother and can retain an abrasive sheet end (not shown) clamped betweenthem pivoted away from clamping lever 200, so that an associatedabrasive sheet is capable of being stretched tightly such that movementof the abrasive sheet relative to the working surface of abrasive sheetcarrier 114 is minimized. The parts of clamping lever 200 explainedhereinabove with regard for FIGS. 1 and 2 are clearly visible and willnot be explained again here.

The procedure for installing an abrasive sheet 16 in manual grindingtool 10 according to FIG. 1 will be explained hereinbelow: Manualgrinding tool 10 with opened tongs 334 is held with one hand. Using theother hand, first abrasive sheet end 19 is inserted at clamping lever 20on the front side of manual grinding tool 10 by pressing against outercontour 27 of clamping lever 22. A gap opens between clamping jaw 22 andlocking surface 23, into which said gap abrasive sheet enters withoutclamping lever 20 having to be actuated separately. Even a smallinserted section of the abrasive sheet end is “automatically” prevented,via strong force, from coming back out, i.e., it is clamped, andclamping lever 20 must be pivoted in the release direction to pull itback out.

When abrasive sheet 16 is slid slightly forward, abrasive sheet end 19is inserted between clamping jaw 22 and locking face 23 so far that itextends past it by approximately 5 mm. As a result, a relatively smallamount of effort is required to clamp first abrasive sheet end 19tightly and securely to its abrasive sheet carrier 14 on the front sideof manual grinding tool 10.

Subsequently, second abrasive sheet end 17 is inserted and locked inopened tongs 34 located on the rear side of abrasive sheet carrier 14.Abrasive sheet 16 is thereby stretched tightly. Since the clamping pointof tongs 1334 moves along a circuit around swivel axis 410 away from thefront side of manual grinding tool 10, abrasive sheet 16 is held tightlyagainst abrasive sheet carrier 140 and can therefore be used with highefficiency for sanding.

To remove abrasive sheet 16 from manual grinding tool 10, clamping lever20 is moved by pressing button 211—as horizontal extension of swing arm21—together with said button around swivel axis 24. Clamping jaw 22,with its outer contour 27, lifts away from abrasive sheet 16 and lockingface 23 in such a manner that abrasive sheet 16 can easily be pulled outof the widening gap.

FIG. 4 shows a top view of abrasive sheet carrier 14 of a manualgrinding tool 100 with a further embodiment of abrasive sheet-clampingdevice 340, 500 according to the invention.

The front side of abrasive sheet carrier 14 is seen on the right,whereby a pivoting lever 500 is shown on its top side, which saidpivoting lever, with its clamping jaw 510, presses an abrasive sheet end155 of an abrasive sheet 150 downward toward the top side of abrasivesheet carrier 14 and retains it there. Pivoting lever 500 is capable ofbeing pivoted against the spring force of a leg spring (not shown) inthe release direction, as indicated by directional arrow 560; when theend position is reached, abrasive strip end 155 can be pulled out underclamping jaw 510. If pivoting lever 500 is pivoted via its handle 520—asshown on the left—in the direction of arrow 550, abrasive sheet end 155is clamped tightly. Since pivoting lever 500 follows sandpaper end 155,when said sandpaper is pulled outwardly, the abrasive sheet is clampedincreasingly more tightly.

Abrasive sheet end 155—shown on the left—is clamped tightly at the rearside of manual grinding tool 1000 between a clamping jaw 340 that iscomposed of an active jaw 360 and a passive jaw 380. Active clamping jaw360 is formed by a wire bracket 370. Said wire bracket 370 is bentnearly in the shape of a semicircle—starting at swivel axis 400 andextending toward the left, as seen in the drawing—whereby it forms thecrossbar-shaped active clamping jaw 360 from a radially inwardly bentregion, bent at a right angle outwardly and/or axially. Said activeclamping jaw extends parallel to the rear transverse edge of abrasivesheet carrier 14 at a distance from it and transitions—on the otherside, with mirror symmetry to the bent region of wire bracket 370—intoan identically semicircularly bent second region that bears with itsrear region on the top side of abrasive sheet carrier 14.

Spring bracket 370 transitions from its region bent in the shape of a“c” at its two symmetrical contact surfaces on the top side of abrasivesheet carrier 14, both of which said spring brackets are bent nearlyperpendicularly outwardly parallel to the top surface of abrasive sheetcarrier 14 into one axle stub 410 each, each axle stub forming—togetherwith one groove 430 each between two projections 440 designed in themanner of abutments—a rocker pivot around swivel axis 400.

Adjacent to axle stub 410, each wire bracket 370 transitions outwardlyinto a 900 bend. On the front side—as shown in the drawing—it extendsparallel to longitudinal axis 370 of handheld oscillating sander 10 andforms a clamping lever 350 with a handle 390. On the rear side—as shownin the figure—it forms a damping piece 355. With clamping tongs 340 inthe clamped position, said damping piece bears against the top side ofabrasive sheet carrier 14 such that relative motion does not occurbetween wire bracket 370 and abrasive sheet carrier 14 when oscillatingsander 10 is operated. As a result, vibrations and disturbing noises areprevented when oscillating sander 10 is operated.

In the clamped position, clamping lever 350 is capable of being hung inlatching hook 450 in an over-latching manner. The crossbar-shaped regionof active clamping jaw 360 thereby bears against an elastic contactsurface 420—which has particularly good grip—of passive clamping jaw380, said contact surface being composed of plastic.

Contact surface 420 of passive clamping jaw 380 is formed by a rubberystrip part that is secured on the outer end of passive clamping jaw 380configured as surface spring. Passive clamping jaw 360 extends parallelto the surface of abrasive sheet carrier 14 and is fixed thereto by thefact that it is clamped tightly under the foot-like end of oscillationbody 160.

Since passive clamping jaw 380 is configured as surface spring, it doesnot need any special means, e.g., a joint, to define swivel axis 400.

As shown on the right, i.e., on the front side, abrasive sheet carrier14 carries an abrasive sheet clamping system that corresponds inprinciple to that according to FIG. 1. The only difference is thatpivoting lever 500 is preloaded in its clamping position by a leg spring(not shown) instead of by a tension spring.

FIG. 5 shows a schematic depiction of active clamping jaw 360 as anelement bent out of a single wire part. It is easy to see how clampinglever 350, after the first right-angled bend, transitions into firstaxle stub 410, and, from there via the second right-angled bend, ittransitions into first semicircular wire bracket 370, from there, viathe third right-angled bend, it transitions into the actual,crossbar-shaped active clamping jaw 360, from there, via the fourthright-angled bend, it transitions into the second, semicircular wirebracket 370, from there, via the fifth right-angled bend, it transitionsinto the second axle stub 410, and from there, via the finalright-angled bend, it transitions into extension 355 serving asoscillating damper, which clamps against top side 140 of abrasive sheetcarrier 14 with preload.

FIG. 6 shows a further variant for oscillation damping of second wirebracket 370 that is elastically clampable in the clamped positionbetween two elastic damping jaws 655, so that vibrations and noises aretherefore suppressed. Damping jaws 650 are located on the top side ofabrasive sheet carrier 14.

FIG. 7 shows a further variant for vibration damping of second wirebracket 370 via a leaf spring 660 which bears outwardly on its archedcircumference. Via its preload, wire bracket 370 and/or axle stub 410are held against abrasive sheet carrier 410 and vibrations aresuppressed.

FIG. 8 shows a fourth variant for oscillation damping of second wirebracket 370 using a damping rubber member 670 positioned around theouter axle stub 410, against the diagonally positioned angular surface671 of which wire bracket 370 bears in the clamped position, and theoscillations of which are suppressed.

FIG. 9 shows a further exemplary embodiment of a passive clamping jaw700 alone, which is not composed of a surface spring 380 as in FIG. 4,but rather of a U-shaped spring wire piece. Between its U-legs 710,passive clamping jaw 700 has a connecting piece 720 on its curvaturewith a contact body 740 made of rubber or plastic that forms a contactsurface 730 for abrasive sheet end to rest against and for activeclamping jaw 360 to engage with (FIG. 4). To dampen oscillations,passive clamping jaw 700 has a crossbar-shaped connecting body 750composed of plastic or rubber, the connecting body being penetrated byU-legs 710.

Ends 760 of U-legs 710 bent inwardly in the shape of a circle form screweyelets that are gripped over by screws or the foot-shaped lower partsof oscillation body 160 and are thereby securable to abrasive sheetcarrier 14.

FIG. 11 is nearly identical to FIG. 1 and shows a manual grinding tool10 (oscillating sander) with a housing 12 that includes a handle on theoutside and an electric motor on the inside (not shown). An abrasivesheet carrier 14 is located at the bottom of housing 12, which, drivenby a motor, is capable of being set into oscillating motion relative tohousing 12 and, as a result, can remove material from a work piece (notshown) via sanding with an abrasive sheet 16 secured tightly underneathon its working surface 15. The grinding dust that is created is capableof being blown out and/or suctioned up from the front side 121 towardthe rear side 122 of manual grinding tool 10 via suction connectingpiece 120. Abrasive sheet 16 rests with its back side against theunderside of abrasive sheet carrier 14.

A clamping means designed as a two-armed clamping lever 20 with a swivelaxis 24 is positioned in the front on top side 13 of abrasive sheetcarrier 14.

Reference is made to the description of FIG. 1 regarding the remainingdetails of clamping lever 20.

As viewed on the right, a clamping-tensioning device configured as tongs34 is located on the rear side 122 of abrasive sheet carrier 14, theclamping-tensioning device deviating from that according to FIG. 1 inthat it is composed of parts of wire and/or spring steel sheet havingintrinsic spring action. It is composed of a clamping lever 35 withactive clamping jaw 36 having mutiple bends and/or curves, the activeclamping jaw conforming in principle to that according to FIG. 5, butwith a slightly altered contour of the curved region. It has a handle 39which forms a two-armed lever which is pivotable around a swivel axis40—which is secured in simple fashion using a screw 510—formed by agroove (not shown) on top side 13 of abrasive sheet carrier 14. Activeclamping jaw 36 is composed of bent spring steel wire. A clamping lever370 made of corrugated spring sheet bearing against the inner contour ofactive clamping jaw 36 when abrasive sheet 16 is clamped is alsopivotable around the geometric extension of pivot axis 40, the clampinglever forming passive clamping jaw 38. The other abrasive sheet end 17that is diametrically opposed to first abrasive sheet end 19 is insertedand retained between passive clamping jaw 38 and active clamping jaw 36.

When tongs 34 with retained sandpaper end 17 are pivoted around swivelaxis 40 in the counterclockwise direction, the distance betweensandpaper ends 17, 19 relative to each other increases. As a result,abrasive sheet 16 is tightened and pulled tightly against the undersideof abrasive sheet carrier 14. The tightening of abrasive sheet 16becomes noticeable via the rear lower edge 118 of cushion 18 that ispressed round in shape.

When tongs 34 are in the clamped position, springy clamping lever 35assumes an end position in which handle 39 is snapped into lockinggroove 49 of lateral latching hook 48. By pressing clamping lever 35toward housing 12, said handle comes out of locking groove 49 and canthereby pivot freely back into its open position. Passive clamping jaw38, which springs back into its own position, thereby acts on saidhandle and carries it along into the “opened” position. Clamping lever35 is capable of being pivoted further by hand to an end positionforming a wide opening slit 500 (FIG. 2) between active clamping jaw 36and passive clamping jaw 38. In this end position, tongs 34 are openedwide and the distance between active clamping jaw 36 and passiveclamping jaw 38 is so great that sandpaper end 17—indicated with thedashed line—can be inserted into tongs 34 quasi blindly and in aself-locating manner without it having to be bent further upward out ofthe plane of working surface 15.

The surface spring 370, which self-tensions passive clamping jaw 38,having the form of a one-and-a-half sine wave with a small amplituderegion toward the clamping point determines and/or limits the clampingforce between active clamping jaw 36 and passive clamping jaw 38 in theclamped state, whereby, when surface spring 270 is short in design, avery strong clamping force is achieved, accompanied by a good hingedjoint function.

If, to replace the abrasive sheet, clamping lever 35 is released fromits clamped position by unlatching it from latching hook 48 and ispivoted around axis 40 in the clockwise direction, the distance betweenthe clamping points of sandpaper ends 17, 19 becomes shorter once more,whereby abrasive sheet 16, relieved of tension, is simultaneouslycapable of being easily removed from opening slit 500.

FIG. 12 shows the horizontally situated tongs 34 with manual grindingtool 10 according to FIG. 11 opened with loosely inserted sandpaper end17. By pivoting clamping lever 35 in the counterclockwise direction,active clamping jaw 36 moves closer to passive clamping jaw 38 andthereby carries sandpaper end 17 along due to its high friction on therubber lining—indicated by the bold line—in the direction toward passiveclamping jaw 38 and clamps it tightly thereto. When active clamping jaw36 is pivoted further, it carries passive clamping jaw with clampedsandpaper end 17 along on its pivot path, thereby tightening abrasivesheet 16 and holding it tightly in the tightened position as a result ofclamping lever 35 which is latched in latching hook 48. The desiredclamped position of abrasive sheet 16 is therefore created.

The means of attaining the object of the invention, according to theinvention, are not limited to the arrangement of a self-clamping leversystem on the side diametrically opposed to the tongs; instead, aconventional clamping lever system with spring preload can also beprovided.

1. A manual grinding tool, in particular an oscillating sander (10),with a housing (12), an abrasive sheet carrier (14), and clamping means(20, 23; 360, 500) for retaining opposite abrasive sheet ends (17, 19;155) of an abrasive sheet (16; 150) which is capable of resting againstabrasive sheet carrier (14), wherein the clamping means (20, 23; 340,500), together with an abrasive sheet end (17, 155) clamped thereto, arecapable of being moved away from the other abrasive sheet end (19, 155)which is also clamped, so that the abrasive sheet (16; 150) is lockableunder tensile stress, whereby the clamping means (20, 23; 340, 500) arecomposed of resilient material.
 2. The manual grinding tool as recitedin claim 1, wherein one of the clamping means (20, 23; 340, 500) isconfigured as tongs (34; 340) and has clamping jaws (36, 38; 360, 380),between which an abrasive sheet end (17, 19; 155) is clampable, andwherein the tongs (34; 340)—with the clamping jaws (36, 38; 360, 380)and the clamped abrasive sheet end (17, 19; 155)—are movable around aswivel axis (40; 400) and are detachably lockable in a pivoted-outposition.
 3. The manual grinding tool as recited in claim 2, wherein oneof the clamping jaws (36, 38; 360, 380) is configured as manuallyoperated active clamping jaw (36; 360), and the other as passiveclamping jaw (38; 380) which is capable of being operated using theactive clamping jaw (36; 360) and pivoted with the same.
 4. The manualgrinding tool as recited in claim 3, wherein the active clamping jaw(36; 360), when closed, rests against the elastically preloaded passiveclamping jaw (38; 380) and carries it—against the elastic preload—intothe fixable clamping position, via pivoting in particular.
 5. The manualgrinding tool as recited in claim 4, wherein the active clamping jaw(36; 360) is part of a two-armed clamping lever (35; 350), one of thelever arms of which serves as a handle (39; 390) which is detachablylockable in its clamped position.
 6. The manual grinding tool as recitedin claim 5, wherein the tongs (34; 340) are pivotable around the swivelaxis (40; 400) between two end positions that define their clamped andreleased positions.
 7. The manual grinding tool as recited in claim 6,wherein the surfaces of the active and passive clamping jaws (36, 38)are very rough and/or have a strong grip.
 8. The manual grinding tool asrecited in claim 3, wherein the active clamping jaw (360) isa—single-component, in particular—bent wire element that is positioneddiametrically opposed—with a crossbar, in particular—to a correspondingsurface of the passive clamping jaw (380) in a manner that allows it tobe pressed together in the manner of tong jaws.
 9. The manual grindingtool as recited in claim 8, wherein the passive clamping jaw (380) is aresilient part that is rigidly located with one end on the top side ofthe abrasive sheet carrier (14).
 10. The manual grinding tool as recitedin claim 9, wherein the passive clamping jaw (380) is a leaf springand/or a resilient wire.
 11. The manual grinding tool as recited inclaim 10, wherein the abrasive sheet (150) is clampable with minimaldeformation such that it fits between the active (360) and passiveclamping jaw (380).
 12. The manual grinding tool as recited in claim 11,wherein the active clamping jaw (360) forms an axle stub (410) withwhich it rests in a recess of the abrasive sheet carrier (14), where itforms the swivel axis (400).
 13. The manual grinding tool as recited inclaim 12, wherein the active clamping jaw (360)—on one side, connectedto the axle stub (410)—forms the clamping lever (350) and, on the otherside, includes means (370, 650, 660, 670) at the end of the other axlestub (410) for vibration damping.
 14. The manual grinding tool asrecited in claim 13, wherein the means for vibration damping aremountable on an extension of the axle stub (410) and bear against theabrasive sheet carrier (14) with preload.
 15. The manual grinding toolas recited in claim 13, wherein the abrasive sheet (16; 150) isinsertable between the clamping jaws (22; 220; 1220; 500) and theabrasive sheet carrier (14), whereby the clamping jaws (22; 220; 1220;500) are capable of being opened merely via contact with the abrasivesheet (16; 150), which said abrasive sheet, when moved against thedirection of insertion, is automatically lockable as a result of thismotion.